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Tiny Light Beam Budges Nanoscale Object

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Scanning electron micrograph of two thin, flat rings of silicon nitride, each 190 nanometers thick and mounted a millionth of a meter apart. Under the right conditions optical forces between the two rings are enough to bend the thin spokes and pull the rings toward one another, changing their resonances enough to act as an optical switch. Image Credit: Cornell Nanophotonics Group

With a bit of leverage, researchers have used a very tiny beam of light with as little as 1 milliwatt of power to move a silicon structure up to 12 nanometers. That’s enough to completely switch the optical properties of the structure from opaque to transparent, they report.

The technology could have applications in the design of nanoscale devices with moving parts—known as micro-electromechanical systems (MEMS)—and micro-optomechanical systems (MOMS), which combine moving parts with photonic circuits, says Michal Lipson, associate professor of electrical and computer engineering at Cornell University. Light can be thought of as a stream of particles that can exert a force on whatever they strike. The sun doesn’t knock you off your feet because the force is very small, but at the nanoscale it can be significant. “The challenge is that large optical forces are required to change the geometry of photonic structures,” Lipson explained.
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